A water pump is usually used to create and maintain a certain amount of water pressure. This is important because there are times when taking a shower or flushing a toilet with a minimal amount of water just isn’t enough. Imagine if you took a shower and only had a trickle of water come out of the shower head. This would not only be frustrating, but most likely cold in the winter time.
A water pump is good for regulating this, and in most RV cases, the water pump is used whether on the road our at an RV park. In many cases the RV park where a person is staying may not have the type of pressure that is conducive for a good shower.